The subject of this invention is a method to stretch stockings in men stocking boarding units, and a device to implement such method.
It is known that, during the production phase, stockings undergo several thermal treatments aimed at granting them adequate features. In particular, stockings undergo a boarding treatment that grants them a permanent set. To perform said boarding, stockings are inserted and stretched on special shapes after which they undergo the thermal treatment, for example by means of special pressure steam chambers.
The currently known automatic boarding units for men stockings consist basically of a turntable equipped with special shapes uniformly distributed along the outline of said turntable, on which stockings are inserted and stretched. The turntable""s rotation leads the stockings inserted on the shapes into a boarding chamber, for instance of the pressure steam type, and then to a drying chamber. Stockings are then extracted from the boarding shapes and sent to the following packing phases.
Stockings produced with this method never have the same length, even if they are of the same size, due to unavoidable unevenness occurring during the production phase. In particular, said length difference is present in the stocking leg.
It is therefore necessary to gather the output stockings from the boarding unit in homogenous length groups.
Automatic machines called matching machines, which execute the matching of men stockings, usually perform this task. The relevant staff operates a matching machine by feeding it with the stockings to be matched, after having individually taken them from the piles of stockings coming from the earlier production phases. Individual stockings must in fact be placed on a mobile shape of the matching machine, exchangeable according to the size of the machined stockings.
Matching machines have a complex structure and function; therefore their cost is rather high. This cost should obviously be added to that of the employed staff.
To remove this inconvenience, it was devised to employ devices capable of stretching the stockings and to apply such devices to the shapes of the boarding units. In practical terms, these devices consist of a pincer coupled to the boarding shape and capable of grasping the so-called cuff of the stocking placed on the shape itself; the pincer keeps the stocking stretched during the boarding phase in the steam chamber, in order to keep the leg of the stocking stretched to a preset length. When the stocking outputs from the boarding chamber it has a permanent set and therefore maintains the constant length imposed by the stretching device.
Said stretching devices, although based on a correct concept, have never been used in practical terms because their costs are very high as well. In fact, it should be considered that boarding units employ a relatively high number of shapes, for example fifteen or twenty, and that each of these should be duplicated for the number of sizes to be produced, for example about twenty. As each boarding shape requires a stretching device, it is evident that the number of these stretching devices would be rather high.
The aim of the present invention is to resolve the above-mentioned drawbacks by devising a method allowing to stretch men stockings in the boarding units for these stockings, in order to keep the stocking leg stretched to the preset length in the steam boarding phase and obtain constant length stockings.
Within the scope of this task, this invention is also aimed at providing a device that can implement such method with a simply conceived structure, a surely reliable operation and versatility of use, as well as a relatively low cost.
The mentioned goals are reached with this method for stretching stockings in men stocking boarding units of the type equipped with an implement mounting several boarding shapes on which the relevant stockings should be inserted; said implement is suited to be led into a steam boarding chamber defined by two shells, movable with respect to each other into a mutual opening and closing position. This method is distinguished in that it provides for grasping the stocking inserted on the relevant boarding shape, in correspondence with the cuff of said stocking and on opposing sides of the boarding shape itself, by means of opposing gripping means bound to said shells of the boarding chamber; to cause the elastic deformation of said gripping means upon the closing of said boarding chamber shells, in order to stretch the stocking leg on said boarding shape at a preset length; to keep stretched said stocking leg during the boarding phase, inside said boarding chamber.